Although rat maternal behavior (MB) is under multi-sensory control, the role of perioral and oral sensations in the regulation of MB is unclear. Because most maternal activities are oral (e.g., placentophagia, licking, retrieving, nest-building, biting intruders), studies to explore the role of cutaneous snout, lip, and chin afferents (surgical anaptia) and anterior tongue touch and taste (local anesthesia; anterior tongue denervation) on parturition; postpartum and hormonally-initiated MB; discrimination of pups on the basis of thermal and tactile cues; and on induction of MB by cohabitation with pups will be conducted. Sensory cues from both pups and the intruder are important in the regulation of maternal aggression. Specifically, the roles of cutaneous snout and lip afferents, nipple stimulation (e.g. suckling), the Vomeronasal Organ-accessory olfactory system and the main olfactory system, and prior cohabitation with an intruder will be assessed. Local mystacial pad anesthesia or surgical anaptia, thelectomy (nipple-removal), Vomeronasal nerve cuts, and intranasal ZnSO4 anosmia will be employed. Pup odors appear to be attractive to lactating dams and aversive to maternally-naive virgins. These assumptions will be tested directly and linked to possible changes in and control by the centrifugal noradrenergic inputs into the olfactory system. These inputs have been linked to sensory recognition, selective attention, and olfactory "imprinting" during reproductive behavior interactions. A knowledge of the stimuli which regulate the expression of a given behavior is essential to a full understanding of that behavior. In people as well as rats, what initiates and influences the amount of parent-young contact is determined largely by both parent and offspring characteristics.